Preinsulated crimpable ferrule-type connectors have long been used to splice insulated wires, particularly the wires of telephone cables. Some connectors of this type are disclosed in U.S. Pat. Nos. 3,320,354 and 3,611,262.
Tools such as the device disclosed in U.S. Pat. No. 3,382,872 have been designed to crimp the connectors onto the wires.
This type of connector and the corresponding tools have been widely accepted by industry. While acceptable for outside use, the insulation on the original connectors is not sufficiently flame retardant to meet current industry standards for use inside buildings. These standards require an insulating material that will not support combustion and will not readily lose its insulating properties should a fire occur.
In response to the demands on industry, the present invention is directed toward the achievement of a flame retardant connector having a Limited Oxygen Index value of at least 28 as determined by testing in accordance with ASTM D2863-70.
Additional requirements were that the flame retardant connector be compatible with the present manufacturing process and crimping equipment. The invention disclosed herein meets the above requirements.
The insulating sheath is a two layer laminate comprised of a paperlike layer of heat resistant polyamide bonded to a layer of tetrafluoroethylene film. The metal ferrule is bonded to the polyamide layer. When the connector is crimped onto wires the sheath follows the ferrule, thus encasing the polyamide layer inside the tetrafluoroethylene layer.